This invention generally relates to an apparatus and method for the transfer of material between vessels, and specifically, for facilitating transfer of hazardous material between spill-control accumulation centers.
Pallet-type accumulation centers are often used for collecting hazardous material spillage or seepage from storage drums. Such accumulation centers may comprise open tub-like vessels, often with a grate spanning the top of each vessel and supported by the vessel sidewalls such that storage containers or drums sit atop the grate, and any hazardous material seepage or spillage flows into the vessel. For example, the Gator(trademark) line of Accumulation Centers, produced by the Justrite Manufacturing Company, and other similar vessels collect storage drum spillage or seepage in this way. The utility of such centers or vessels may be enhanced by providing for the transfer of the collected material between multiple vessels. Increased spill collecting capacity and increased efficiency permit safe handling of multiple drums with lower profile vessels. However, many of the existing transfer systems or devices are complex and costly: they may often require costly special manufacturing in anticipation of such use. For example, U.S. Pat. No. 5,562,047, to Forney et al. (xe2x80x9cthe ""047 patentxe2x80x9d), describes a module connection assembly that physically connects two spill deck modules together and provides for fluid transfer between the modules.
This type of design relies on a seal created by the interaction of fasteners, washers, and the inside walls of the vessels. Specifically, as shown in FIG. 6 of the ""047 patent, flanged hex nuts 66 and 66xe2x80x2 are threaded onto the ends of connection member 58 and tightened until a seal is created between the inside surface of the vessel wall and the nut flange. The resulting seal is perpendicular to the connection member and, therefore, introduces a potential for leakage if the vessels are jostled or moved relative to each other. Specifically, relative motion between the vessel aperture and the connection member, due to vibration, minor impacts and jostling, may create a gap between the vessel wall and the flange of the hex nut causing a leak in the seal. Additionally, any deflection of the vessel sidewalls, due to the weight of containers supported thereby, may induce relative motion between the sidewall and the nut flange, thus potentially misaligning the sidewall aperture and the nut flange enough to create a leak. This potential for leakage may be magnified as heavy containers or drums are shifted or rolled from one connected vessel to another.
Moreover, this type of threaded tube design both structurally joins two vessels and provides for fluid communication between them. Such a design requires the selection of a single localized position on each vessel that is conducive to both fluid communication and structural support. As a result, the effectiveness and versatility of such a device may be limited by the potential for malfunction or leakage caused by inappropriate mounting in a location that does not support both fluid transfer and effective structural connection.
For example, if this type of design is utilized with slightly angled vessel sidewalls, or sidewalls with small external protrusions on one or both of the respective mating sidewalls, the sidewalls may not flushly mate in the location of the connection device. Under these conditions, tightening the nuts applies a concentrated force that tends to deflect the surface of the spaced-apart sidewalls in this region, thus breaking the seal. Assuming that a seal can be generated, however, such a seal is also susceptible to leakage if the vessels are moved, jostled or exposed to vibration. The lack of lateral support or structure in the flange nuts may thus tend to allow undesirable deflection of the vessel sidewalls.
Moreover, multi-component transfer systems, such as that described in the ""047 patent, are not universally applicable. Specifically, such a threaded connection member must include some sort of backing member, against which a mating nut can be tightened to provide a seal. A vessel sidewall may provide a suitable backing if it is parallel to the nut flange. However, if the sidewalls of vessels to be joined are not both parallel to each other, and normal to the connection member, for example, this type of connection member may introduce concentrated, leak-inducing stresses and sidewall deflection, as discussed above. Thus, a structural connection member that can better manage such forces and stresses is desirable.
Additionally, a location that supports an effective structural connection may not coincide with the desired fluid connection location. It may be advantageous, for example, to position the connection member near the bottom of a vessel to provide for earlier communication of accumulated material. This may be due to environmental concerns regarding storage of volatile materials in open vessels or the difficulty of moving various storage devices. Locating the apertures near the bottoms of connected vessels provides a flowpath that facilitates near-complete removal of the accumulated material from both vessels. However, the configuration of the vessels may not always facilitate or support an efficient structural connection in the same location as the fluid connection. For example, it may be difficult to use a nut-tightening tool near the bottom of the vessel where there is little tool clearance. The types of connection devices described above cannot avoid this problem.
Furthermore, a rigid connection member, as in the prior type of design, will not provide an effective seal if the vessels to be joined are slightly vertically staggered. For example, a vessel may rest on a pedestal, or an uneven shop floor, such that it is otherwise vertically offset from a joined vessel. In this case, the rigidity of the vessel walls and of the connection member will prevent an effective seal at their interface, particularly if the uneven surface forces the connection member into a non-perpendicular relationship with the sidewalls. The interface between rigid nut flanges and vessel walls, in this case, is subject to the same sealing problems inherent in a perpendicularly-sealing interface between the vessel walls and the connection device, as described above. Moreover, utilizing mass-produced, multi-component systems including independently manufactured apertures, connection members, and flange nuts also introduces inherent build variations or tolerances that exacerbate these issues.
Also, threaded metal connectors may be susceptible to corrosion, which increases the possibility of leaks and the time and effort needed to remove or disassemble such connectors. The fabrication of complex devices, such as those including threaded tubes and nuts, also results in a complex, costly connection method that may be difficult to integrate with containers that do not have smooth surfaces surrounding the connection apertures. Specifically, securing a nut to a threaded connection member requires adequate clearance from walls or other internal features of the vessel to allow the use of a wrench, socket, or other tool during installation. Additionally, transfer systems incorporating a threaded connection member secured by nuts can loosen and cause leakage over time, particularly if exposed to vibration and changes in temperature.
Thus, a need exists for a secure, low-cost vessel connection apparatus and method that provides a leak proof seal, is simple to install, is corrosion resistant, and which may dissipate applied forces along a vessel wall, thus reducing vessel wall deflection and relative motion between vessel sidewalls and fluid connection members.
Accordingly, it is an object of this invention to provide a transfer apparatus that facilitates the transfer of materials between vessels, and that provides and maintains a flexible, leak-proof seal and a secure connection between the vessels, particularly if they are moved or jostled relative to one another, or if the joined vessels rest on a slightly uneven surface.
Another object of the invention is to decrease the potential for leakage of a fluid connection between vessels that does not, in addition, structurally connect the vessels.
It is a further object of the invention to provide an inherently corrosion-resistant apparatus for the transfer of material between vessels.
An additional object of the invention is the provision of a holding device that securely holds together vessels fluidly connected by the transfer apparatus of the invention, and that may be positioned independently of the transfer apparatus, so that sidewall stresses may be reduced, particularly in the area of the fluid connection.
Additionally, it is an object of this invention to provide such an apparatus that is easy to install and that has a very low cost.
Another object of the invention is to provide a method for fluidly connecting vessels that fulfills all of the above-stated objectives.
To fulfill the stated objects, among others, an invention and method are disclosed herein that provide for collection and controlling of the accumulation of materials within a plurality of vessels. Specifically, the invention provides an apparatus that includes a tube of sufficient length, with an outer wall and a plurality of ends that extend through apertures in the sidewalls of vessels to be fluidly connected, such that the tube provides a flow path for material between the interiors of the vessels. The tube may consist of a rigid material that also prevents adjacent vessels from separating due to forces acting on one or both of the vessels, in a direction transverse to the longitudinal axis of the tube. Moreover, the length of the tube may be selected in order to provide a desired level of rigidity in this direction. The invention may also include a sealing interface between at least two portions of the tube outer wall and at least two vessel apertures. The sealing interface may further be substantially coaxial with the tube at each sealed interface. Moreover, the apertures may also be provided at various depths of the vessels, to facilitate fluid transfer at corresponding vessel fill levels.
In order to provide or enhance a leak-proof seal, the sealing interface of the apparatus may comprise a grommet to be disposed in a vessel sidewall aperture before the respective tube end is inserted. The grommet may provide multiple sealing surfaces, viz., one coaxial seal between the tube and the aperture, and additional seals on each of the interior and exterior surfaces of the vessel sidewall in the immediate vicinity of the aperture. The apparatus may also include at least one C-shaped channel member, or clip, that straddles and grips the top edges of substantially abutting sidewalls of adjacent vessels, thus preventing their separation due to forces acting on one or both of the vessels, in the direction of the longitudinal tube axis. Moreover, the clip may include one or more tabs protruding into its interior, to resist removal from the abutting sidewalls once installed. The clip may also be a separate component from the tube, capable of placement separately from the tube.
Moreover, each of the components of the apparatus may be manufactured of a material that resists corrosion or attack by hazardous substances. The tube may also be at least partially fabricated of a lubricious substance that facilitates ease of insertion into the grommets, or the tube wall may be at least partially coated with a lubricious substance.
The method of the presently described invention may consist of the steps necessary to provide the transfer apparatus described above, and an additional step of determining a depth at which the material transfer is desirable.